JP7450727B2 - Hydrocarbon adsorbents, exhaust gas purification catalysts, and exhaust gas purification systems - Google Patents

Description

The present invention relates to a hydrocarbon adsorbent, an exhaust gas purification catalyst, and an exhaust gas purification system that can adsorb and store hydrocarbons in exhaust gas discharged from internal combustion engines such as automobiles.

Exhaust gas from internal combustion engines such as automobiles that use gasoline as fuel contains hydrocarbons (HC) from unburned fuel, carbon monoxide (CO) from incomplete combustion, and nitrogen oxides (NOx) from excessive combustion temperatures. Contains harmful ingredients. Exhaust gas purification catalysts are used to treat exhaust gas from such internal combustion engines. Such an exhaust gas purification catalyst, for example, oxidizes hydrocarbons (HC) and converts them into water and carbon dioxide (CO ₂ ), oxidizes CO and converts them into CO ₂ , and reduces NOx and converts them into nitrogen. to purify. For example, platinum group metals are used in such exhaust gas purification catalysts, and among them, platinum group metals such as platinum (Pt), palladium (Pd), and rhodium (Rh) are particularly used. Further, the exhaust gas purification catalyst uses, as a constituent component, a hydrocarbon adsorbent that has the ability to adsorb and store hydrocarbons in the exhaust gas.

It is known that such an exhaust gas purification catalyst is relatively inefficient in treating exhaust gas in a low temperature environment such as in a cold start state of an internal combustion engine. Patent Document 1 discloses that in order to improve the efficiency of exhaust gas purification in a cold start state, a zeolite catalyst containing a base metal, a noble metal, and a zeolite, one or more platinum group metals, and one or more inorganic oxidizers are used. A cold start catalyst is disclosed that includes a solid support and a supported platinum group metal catalyst. Patent Document 1 discloses, for example, BEA type zeolite, MFI type zeolite, CHA type zeolite, etc. as zeolites contained in a cold start catalyst.

Special Publication No. 2014-519975

However, in the cold start catalyst disclosed in Patent Document 1, after storing hydrocarbons in a cold start state, when high temperature exhaust gas flows in and warms the catalyst, the storage occurs before the catalyst is sufficiently activated. Since the hydrocarbons are desorbed, the hydrocarbons may be discharged without being purified. Hydrocarbon adsorbents can adsorb and store hydrocarbons up to a temperature sufficient to activate the catalyst, and at the temperature that activates the catalyst, the adsorbed and stored hydrocarbons can be desorbed. Performance is required. Furthermore, since exhaust gas purification catalysts are exposed to high-temperature exhaust gas, there is also a demand for hydrocarbon adsorbents using zeolite, which has high heat resistance.

Therefore, the present invention has developed a hydrocarbon adsorbent that can adsorb hydrocarbons, store the adsorbed hydrocarbons up to a relatively high temperature, desorb the hydrocarbons at a relatively high temperature, and has excellent heat resistance. Its purpose is to provide materials, exhaust gas purification catalysts, and exhaust gas purification systems.

In the present invention, at least one metal selected from the group consisting of transition metals belonging to Groups 3 to 12 of the periodic table, amphoteric metals belonging to Groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals is added to zeolite. Provided is a hydrocarbon adsorbent containing a multi-pore zeolite contained outside the framework, in which the content of the metal is 9% by mass or less based on the multi-pore zeolite containing the metal.

The present invention provides an exhaust gas purification catalyst comprising a base material, a hydrocarbon adsorption section including the hydrocarbon adsorbent on the base material, and a purification catalyst section on the hydrocarbon adsorption section.

The present invention provides an exhaust gas comprising a base material, a hydrocarbon adsorption section including the hydrocarbon adsorbent and Rh on the base material, and a purification catalyst section containing Pd on the hydrocarbon adsorption section. Provide purification catalysts.

The present invention includes an internal combustion engine, a first exhaust gas purification catalyst provided upstream in an exhaust gas flow path connected to the internal combustion engine, and an exhaust gas flow rate in the exhaust gas flow path that is lower than the first exhaust gas purification catalyst. a second exhaust gas purification catalyst provided on the downstream side of the direction, the second exhaust gas purification catalyst is the exhaust gas purification catalyst, and the platinum group metal in the second exhaust gas purification catalyst is Provided is an exhaust gas purification system in which the content ratio of is 0.1 g/L or more and 3.0 g/L or less based on the volume of the second exhaust gas purification catalyst.

The present invention is an exhaust gas purification system comprising an internal combustion engine and a single exhaust gas purification catalyst in an exhaust gas flow path connected to the internal combustion engine, wherein the exhaust gas purification catalyst is the above-mentioned exhaust gas purification catalyst. Provides exhaust gas purification systems.

The present invention provides an exhaust gas purification system comprising an internal combustion engine and a plurality of exhaust gas purification catalysts provided in an exhaust gas flow path connected to the internal combustion engine, the exhaust gas purification system comprising: an internal combustion engine; The first exhaust gas purification catalyst disposed on the most upstream side in the direction provides an exhaust gas purification system in which the first exhaust gas purification catalyst is the exhaust gas purification catalyst.

The present invention brings a combustion exhaust gas containing hydrocarbons into contact with the exhaust gas purification catalyst to adsorb the hydrocarbons on the exhaust gas purification catalyst, and then removes the hydrocarbons from the exhaust gas purification catalyst at a temperature of 170°C or higher. A method for treating exhaust gas includes desorbing hydrocarbons. When water is contained in the combustion exhaust gas, hydrocarbons are repeatedly adsorbed, desorbed, and re-adsorbed onto the exhaust gas purification catalyst at temperatures below 200°C. Behavior tends to be complex. Even if water is contained in the combustion exhaust gas, if the temperature is below 170°C, the hydrocarbons will not be adsorbed again to the exhaust gas purification catalyst, and the hydrocarbons will be adsorbed or desorbed by the exhaust gas purification catalyst. Let go. If the temperature is 170°C or less, even if water is included in the combustion exhaust gas, the hydrocarbons will not be absorbed into the exhaust gas purification catalyst without considering re-adsorption of the hydrocarbons to the exhaust gas purification catalyst. adsorption or desorption can be evaluated. The present invention makes it possible to adsorb and store hydrocarbons at a temperature of 170°C until activation, and after activation, the exhaust gas can be purified by desorbing the adsorbed hydrocarbons. Provide a method for processing.

The hydrocarbon adsorbent provided by the present invention contains multi-pore zeolite that contains a specific metal outside the zeolite skeleton, and can adsorb and store hydrocarbons up to relatively high temperatures, for example, at temperatures as high as 170°C or higher. At this temperature, stored hydrocarbons can be desorbed. Furthermore, this hydrocarbon adsorbent has excellent heat resistance, and can improve hydrocarbon removal performance in an exhaust gas purification catalyst using this hydrocarbon adsorbent and an exhaust gas purification system including the exhaust gas purification catalyst.

FIG. 1 is a schematic perspective view showing an exhaust gas purification catalyst. FIG. 2 shows a first example of an exhaust gas purification catalyst, and is a partially enlarged cross-sectional view. FIG. 3 shows a second example of the exhaust gas purification catalyst, and is a partially enlarged cross-sectional view. FIG. 4 is a schematic configuration diagram showing a first example of an exhaust gas purification system. FIG. 5 is a schematic configuration diagram showing a second example of the exhaust gas purification system. FIG. 6 is a schematic configuration diagram showing a third example of the exhaust gas purification system. FIG. 7 shows the X-ray diffraction spectrum of the obtained MSE type zeolite. FIG. 8 shows the X-ray diffraction spectrum of the obtained EON type zeolite.

Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiment described below.

An example of an embodiment of the present invention is at least one selected from the group consisting of transition metals belonging to groups 3 to 12 of the periodic table, amphoteric metals belonging to groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals. It contains a multi-pore zeolite containing one type of metal outside the zeolite skeleton, and the content ratio of the metal is 9% by mass or less with respect to the multi-pore zeolite containing the metal. The hydrocarbon adsorbent is at least one selected from the group consisting of transition metals belonging to Groups 3 to 12 of the periodic table, amphoteric metals belonging to Groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals. By containing a multi-pore zeolite containing a metal outside the zeolite skeleton, it is possible to adsorb hydrocarbons at a relatively low temperature of, for example, about 50°C, and to store hydrocarbons at a relatively high temperature of, for example, up to 200°C. , it is possible to desorb stored hydrocarbons at relatively high temperatures, for example above 200°C. In addition, if moisture is contained in the exhaust gas, the adsorption, desorption, and re-adsorption of hydrocarbons by the hydrocarbon adsorbent can be evaluated up to 170℃ without considering re-adsorption. Hydrocarbons can be stored up to relatively high temperatures of 170° C. and hydrocarbons stored at temperatures above 170° C. can be desorbed.

Zeolites have a crystalline or paracrystalline aluminosilicate crystal structure composed of SiO ₄ and AlO ₄ tetrahedral repeating units. The units forming the skeleton structure of zeolite are sometimes described as TO ₄ units. The skeletal structure of zeolite is assigned a three-letter uppercase structural code defined by the International Zeolite Society. This structure can be confirmed by the Database of Zeolite Structures, Structure Commission of the International Zeolite Association.

Multipore zeolite is a zeolite that has multiple types of pore structures with different sizes. Examples of the multipore zeolite used in the embodiments of the present invention include zeolites containing large tunnel-type pores and small pores in cages as a pore structure. Tunnel-type pores may also be referred to as linear-type pores, and may be referred to herein as "tunnel-type (straight-line) pores." Moreover, the multipore zeolite may further contain large pore cages. Large tunnel-type (linear) pores include tunnel-type (straight) pores with up to 12-membered rings, and tunnel-shaped (straight-line) pores with up to 10-membered rings. Tunnel type (straight line type) pores having a ring can be mentioned. Examples of large-pore cages include cages with rings of 10 or more members, such as cages with up to 10 members. Examples of small-pore cages include cages with a maximum ring size of 8 members or less, such as cages with a maximum ring size of 8 members and cages with a maximum ring size of 6 members. The multipore zeolite used in the embodiments of the present invention includes, for example, tunnel-type (straight) pores having up to 12-membered rings, cages having up to 10-membered rings, and cages having up to 6-membered rings (6-membered rings and MSE type zeolites have tunnel-type (straight) pores with up to 12-membered rings (cages consisting of 4-membered rings), and cages with up to 8-membered rings (cages with 8-membered, 6-membered, and 4-membered rings). ), and MOR type zeolites having tunnel-type (straight) pores having a maximum of 12-membered rings and cages having a maximum of 8-membered rings. Among these, MSE type zeolites have tunnel-type (straight) pores with up to 12-membered rings, cages with up to 10-membered rings, cages with up to 6-membered rings, and tunnel-type (straight) zeolites with up to 12-membered rings. ) EON type zeolites having pores and cages of up to 8-membered rings are preferred, and MSE type zeolites are particularly preferred. In addition, BEA type zeolites, which only have tunnel-type (straight) pores with a maximum of 12-membered rings, and MFI-type zeolites, which have only tunnel-type (straight) pores with a maximum of 10-membered rings, differ depending on the type of pore structure. Since there is only one, it does not correspond to multipore zeolite.

MSE type zeolite has a tunnel type (straight type) with a maximum of 12-membered rings, a cage pore with a maximum of 10-membered rings, and a cage with a maximum of 6-membered rings (a cage consisting of a 6-membered ring and a 4-membered ring). The crystal structure of a typical MSE type zeolite is tetragonal and belongs to the P4 ₂ /mnm space group. Note that the space group may change when MSE type zeolite is modified with metal ions. In addition, typical MSE type zeolite has a lattice constant a of 18.2461 angstroms (a = 18.2461 Å), which indicates the length of the axis of the unit cell, and a lattice constant b of 18.2461 angstroms (b = 18.2461 Å). , the lattice constant c is 20.5569 angstroms (c=20.5569 Å), and the angles α, β, and γ between the axes of the unit cell are 90 degrees (α=90.000°, β=90. 000°, γ=90.000°). For the crystal structure of zeolite, reference can be made to the database of Zeolite Structures, Structure Commission of the International Zeolite Association.

EON type zeolite has tunnel-type (linear) pores with a maximum of 12-membered rings and cages with a maximum of 8-membered rings (a cage consisting of an 8-membered ring, a 6-membered ring, and a 4-membered ring). The crystal structure of a typical EON type zeolite is orthorhombic and belongs to the Pmmn space group. Note that the space group may change when EON type zeolite is modified with metal ions. In addition, typical EON type zeolite has a lattice constant a of 7.5709 angstroms (a = 7.5709 Å), which indicates the length of the axis of the unit cell, and a lattice constant b of 18.1480 angstroms (b = 18.1480 Å). , the lattice constant c is 25.9324 angstroms (c=25.9324 Å), and the angles α, β, and γ between the axes of the unit cell are 90 degrees (α=90.000°, β=90. 000°, γ=90.000°).

The SiO ₂ /Al ₂ O ₃ molar ratio of the multi-pore zeolite is preferably 10 or more and 600 or less. The SiO ₂ /Al ₂ O ₃ molar ratio of the multi-pore zeolite may be 12 or more, 15 or more, 18 or more, 20 or more, and 500 or less. 400 or less, 300 or less, or 250 or less. The SiO ₂ /Al ₂ O ₃ molar ratio of the multi-pore zeolite is more preferably 12 or more and 500 or less, even more preferably 13 or more and 400 or less, and even more preferably 15 or more and 250 or less. Particularly preferred. When the SiO ₂ /Al ₂ O ₃ molar ratio of the multi-pore zeolite is 10 or more, the crystal structure is stable and it has excellent heat resistance. In addition, when the SiO ₂ /Al ₂ O ₃ molar ratio of the multi-pore zeolite is 600 or less, transition metals belonging to groups 3 to 12 of the periodic table, amphoteric metals and alkali metals belonging to groups 13 and 14 of the periodic table, At least one metal ion selected from the group consisting of , and alkaline earth metals is easily ion-exchanged with a group containing an oxygen atom that becomes a Brønsted acid site adjacent to the Al atom of the multipore zeolite, and the zeolite skeleton Contained outside. The SiO ₂ /Al ₂ O ₃ molar ratio contained in the multi-pore zeolite or the hydrocarbon adsorbent described later can be determined by determining the amount of Si by elemental analysis using, for example, a scanning fluorescent X-ray analyzer (ZSX Primus II, manufactured by Rigaku Corporation). The SiO ₂ /Al ₂ O ₃ molar ratio can be measured from the obtained Si and Al amounts.

An example of an embodiment of the present invention is that the multipore zeolite is a group consisting of transition metals belonging to Groups 3 to 12 on the periodic table, amphoteric metals, alkali metals, and alkaline earth metals belonging to Groups 13 and 14 on the periodic table. At least one metal selected from the following is contained outside the zeolite skeleton. The metal is preferably introduced into the multipore zeolite by ion exchange, but the metal may be modified as an oxide to the multipore zeolite. The metal introduced by ion exchange and the metal modified as an oxide may coexist. When the multipore zeolite is ion-exchanged with ions of the metal, the cations present in the pores of the multipore zeolite function as acid sites and can chemically adsorb hydrocarbons. By exchanging metal ions with multipore zeolite that has been exchanged with basic ammonium ions, the generation of protons (H ⁺ ) can be minimized, and the ions of multipore zeolite can be By exchanging it, it is possible to suppress the generation of hydroxyl groups in the zeolite skeleton. Therefore, multipore zeolite preferentially adsorbs hydrocarbons at relatively low temperatures of, for example, about 50°C, and at relatively low temperatures of, for example, 200°C or higher. Hydrocarbons can be stored up to high temperatures and can be desorbed at relatively high temperatures, for example above 200°C. In addition, if the exhaust gas contains moisture, multipore zeolite can be used to remove transition metals belonging to groups 3 to 12 on the periodic table, amphoteric metals, alkali metals, and alkaline earth metals belonging to groups 13 and 14 on the periodic table. By containing at least one metal selected from the group consisting of outside the zeolite skeleton, multipore zeolite can absorb hydrocarbons without considering re-adsorption among hydrocarbon adsorption, desorption and re-adsorption. Hydrocarbons can be stored to relatively high temperatures up to 170°C at which adsorption and desorption can be evaluated, and hydrocarbons stored at temperatures above 170°C can be desorbed.

Multi-pore zeolite has ion exchange sites in the zeolite pores consisting of transition metals belonging to groups 3 to 12 of the periodic table, amphoteric metals belonging to groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals. At least one metal selected from the group may be ion-exchanged. "Ion exchange site in zeolite pores" specifically means a group containing an oxygen atom that serves as a Brønsted acid site adjacent to an Al atom that is part of the T site that constitutes the skeleton. That is, multipore zeolite is ion-exchanged at the Brønsted acid sites of SiO ₄ and AlO ₄ tetrahedral repeating units that constitute the zeolite skeleton, and contains a specific metal outside the zeolite skeleton. Metals are ion-exchanged at the ion-exchange sites of the multi-pore zeolite, and because the metals exist outside the zeolite skeleton, hydrocarbons are preferentially adsorbed, and the hydrocarbon adsorption ability can be improved.

At least one selected from the group consisting of transition metals belonging to Groups 3 to 12 of the periodic table, amphoteric metals belonging to Groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals contained outside the zeolite framework of the multipore zeolite. The content ratio of one type of metal is 9% by mass or less, preferably 8% by mass or less, more preferably 7% by mass or less, and may be 1% by mass or more, based on the metal-containing multipore zeolite. It is preferably 1.2% by mass or more, and more preferably 1.5% by mass or more. When the content of the specific metal contained in the multipore zeolite is 9% by mass or less, a decrease in heat resistance of the metal-containing multipore zeolite can be suppressed. In particular, if a specific metal is introduced in such a manner as to replace Si in the multipore zeolite skeleton, and the metal content increases, this is not preferable because the heat resistance of the multipore zeolite tends to decrease. When the multi-pore zeolite contains multiple types of specific metals, the metal content ratio means the total of the multiple types of specific metals.

The transition metals belonging to groups 3 to 12 in the periodic table contained in multipore zeolite are iron (Fe), palladium (Pd), rhodium (Rh), platinum (Pt), manganese (Mn), nickel (Ni), and zinc. (Zn), silver (Ag), copper (Cu), titanium (Ti), vanadium (V), chromium (Cr), cobalt (Co), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), and at least one element selected from the group consisting of ruthenium (Ru). In this specification, metals of group 12 in the periodic table are also included in transition metals. The amphoteric metals belonging to Groups 13 and 14 in the periodic table contained in multipore zeolite include aluminum (Al), gallium (Ga), indium (In), thallium (Tl), germanium (Ge), tin (Sn), and At least one element selected from the group consisting of lead (Pb) is included. Amphoteric metals belonging to Groups 13 and 14 of the periodic table contained outside the zeolite framework may not contain aluminum (Al); The metal may be at least one element selected from the group consisting of gallium (Ga), indium (In), thallium (Tl), germanium (Ge), tin (Sn), and lead (Pb). . The alkali metal contained in the multipore zeolite may be at least one ion selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). preferable. The alkaline earth metal contained in the multipore zeolite is preferably at least one selected from the group consisting of calcium (Ca), strontium (Sr), and barium (Ba). The metals contained in multi-pore zeolite are Fe, Pd, Rh, Pt, Mn, Ni, Zn, Ag, Cu, Ti, V, Cr, Co, Zr, Nb, Mo, Tc, Ru, Al, Ga, In. , Tl, Ge, Sn, Pb, Li, Na, K, Rb, Cs, Ca, Sr, and Ba. Moreover, the multipore zeolite may contain magnesium (Mg).

The metal contained outside the zeolite skeleton of the multi-pore zeolite may be at least one selected from the group consisting of Mn, Fe, Ni, Cu, Zn, Ga, Rh, Pd, Ag, Sn, Sc and Pt. More preferred. In the multipore zeolite, the ion exchange sites are ion exchanged with at least one metal selected from the group consisting of Mn, Fe, Ni, Cu, Zn, Ga, Rh, Pd, Ag, Sn, Sc, and Pt. As a result, the hydrocarbons stably adsorbed within the pores can chemically adsorb onto the metal, allowing them to exist even more stably within the pores, making it possible to store hydrocarbons up to higher temperatures. The ion exchange sites of the multipore zeolite may be ion-exchanged with hydrogen ions in addition to metal ions.

Multi-pore zeolite contains one metal selected from the group consisting of transition metals belonging to groups 3 to 12 of the periodic table, amphoteric metals belonging to groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals. It is preferable that the metal/Al ratio, which is the molar ratio of the metal contained outside the zeolite skeleton of the multipore zeolite and Al, is in the range of 0.01 or more and 2.5 or less, When multiple types of metal species (M _x1 , M _x2 ,...) are included, the total value of the molar ratio of each metal (M _x1, M _x2, ...) and Al (M _x1 /Al+M _x2 /Al+ ...) is preferably included in a range of 0.01 or more and 2.5 or less. It is preferable that the metal/Al ratio, which is the molar ratio of metal and Al contained outside the zeolite skeleton of the multipore zeolite, is in the range of 0.01 or more and 2.5 or less because the zeolite structure has stability. It is more preferable that the metal/Al ratio, which is the molar ratio of metal and Al contained outside the zeolite skeleton of the multipore zeolite, is in the range of 0.05 or more and 2.5 or less because it has excellent hydrocarbon (HC) adsorption performance. . The amounts of elements M and Al contained in the multipore zeolite or the exhaust gas purifying composition described below can be measured, for example, by elemental analysis using a scanning fluorescent X-ray analyzer (ZSX Primus II, manufactured by Rigaku Co., Ltd.). .

The multipore zeolite may contain phosphorus or sulfur, and preferably contains phosphorus. When multi-pore zeolite contains phosphorus or sulfur, the parts that cause defects in the skeletal structure are likely to be modified with phosphorus or sulfur, and the parts that cause defects in the skeletal structure are modified with phosphorus or sulfur. Even when placed in a harsh thermal environment, the skeletal structure of the multipore zeolite can be maintained and its heat resistance can be improved. Phosphorus or sulfur generated from a phosphorus source or a sulfur source is, for example, in the form of a phosphate ion or a sulfate ion, and is more likely to bind to a Lewis acid site, which is a metal ion, than to a Brønsted acid site. Multi-pore zeolite maintains Brønsted acid sites, which are active sites for the oxidation of adsorbed hydrocarbons (HC), and forms a skeleton by binding phosphate ions or sulfate ions to metal ions that cause defects in the skeleton structure. Since the structure is maintained, the skeletal structure can be maintained and heat resistance can be improved while maintaining hydrocarbon purification performance even when placed in a severe thermal environment.

When the multipore zeolite contains phosphorus, the P/Al molar ratio, which is the molar ratio of phosphorus to aluminum in the phosphorus-containing multipore zeolite, is preferably in the range of 0.4 or more and 1.1 or less. The P/Al molar ratio is more preferably within the range of 0.8 or more and 1.0 or less. The P/Al molar ratio, which is the molar ratio of phosphorus (P) to Al as the T atom (center atom) of the TO ₄ unit forming the skeletal structure of the multi-pore zeolite, is within the range of 0.4 to 1.1. If present, the phosphorus contained in the multipore zeolite is modified to the Lewis acid sites formed by Al, and the Brønsted acid sites, which are active sites for the oxidation of adsorbed hydrocarbons (HC), are maintained, resulting in improved purification performance. It is possible to suppress defects in the skeletal structure while maintaining the skeletal structure, maintain the skeletal structure even under severe thermal environments, and further improve heat resistance. If the P/Al molar ratio in the phosphorus-containing multipore zeolite is within the range of 0.4 or more and 1.1 or less, defects in the skeletal structure are suppressed and hydrocarbon adsorption performance and purification performance are maintained. be able to. The amount of aluminum (Al) and the amount of phosphorus (P) in the phosphorus-containing multipore zeolite can be determined using a scanning fluorescent X-ray analyzer (for example, manufactured by Rigaku Co., Ltd.), as in the method described in the Examples below. The amount of aluminum (Al) and the amount of phosphorus (P) in the multipore zeolite containing can be measured and calculated from the obtained measured values.

The BET specific surface area A of the multipore zeolite is preferably in the range of 400 m ² /g or more and 1000 m ² /g or less. When the BET specific surface area of the multi-pore zeolite is within the range of 400 m ² /g or more and 1000 m ² /g or less, the amount of hydrocarbon adsorption per unit weight of the multi-pore zeolite is large, resulting in excellent hydrocarbon (HC) adsorption performance. . The BET specific surface area of the multipore zeolite is more preferably 450 m ² /g or more. In order to maintain the skeletal structure even when placed in a harsh thermal environment, the BET specific surface area of the multipore zeolite is preferably 800 m ² /g or less, and even if it is 700 m ² /g or less. It may be 600 m ² /g or less.

The ratio B/A of the BET specific surface area A of the multi-pore zeolite before heat treatment and the BET specific surface area B of the multi-pore zeolite after heat treatment that satisfies the following heat treatment conditions (1) to (5) is 0.35 or more and 1 or less It is preferable that it is within the range of . If the ratio B/A of the BET specific surface area A of the multipore zeolite before heat treatment and the BET specific surface area B of the multipore zeolite after heat treatment is 1, the structure of the multipore zeolite will not change before and after the heat treatment. , which means that the structure is maintained. If the BET specific surface area ratio B/A of the multipore zeolite before and after heat treatment is within the range of 0.35 or more and 1 or less, the micropore structure remains relatively stable even when placed in a harsh thermal environment. This is preferable because it is maintained. The ratio B/A of the multipore zeolite specific surface area before and after heat treatment is more preferably in the range of 0.4 or more and 1 or less, even more preferably in the range of 0.3 or more and 1 or less, and 0.5 or more. It is even more preferably within the range of 1 or less, and particularly preferably within the range of 0.5 or more and 0.9 or less.
Heat treatment conditions (1) Temperature: 850℃
(2) Time: 25 hours (3) Atmosphere: Atmosphere containing 10 volume % water vapor (H ₂ O), vaporize water vapor from a water tank, adjust the saturated water vapor pressure depending on the temperature, and create 10 volume % water vapor. The atmosphere shall be one containing:
(4) Model gas distribution mode: The model gas in (5) below is alternately circulated at 3 L/min for 80 seconds and Air at 3 L/min for 20 seconds.
(5) Model gas: The total of C ₃ H ₆ , O ₂ and N ₂ is 3 L/min, C ₃ H ₆ is 70 mL/min, O ₂ is 70 mL/min, and the balance is N ₂ .

Among multi-pore zeolites, MSE type zeolite diffracts at a diffraction angle position of 21.7°±1.0°, which represents the diffraction index (420) of the X-ray diffraction spectrum of MSE type zeolite. The ratio D/C of the peak intensity C of the diffraction index (420) before heat treatment and the peak intensity D of the diffraction index (420) after heat treatment that satisfies the heat treatment conditions of (1) to (5) is It is preferably within the range of 0.3 or more and 1.5 or less. In the X-ray diffraction spectrum of MSE type zeolite, the diffraction angle (2θ) representing the diffraction index (420) appears at a position of 21.7° ± 1.0°, which is the peak intensity C before heat treatment and the peak intensity D after heat treatment. It is preferable that the peak intensity ratio D/C is within the range of 0.3 or more and 1.5 or less, in order to maintain the skeletal structure even when placed in a severe thermal environment. The peak intensity ratio D/C is more preferably in the range of 0.4 or more and 1.4 or less, even more preferably in the range of 0.5 or more and 1.3 or less, and more preferably 0.6 or more and 1.3 or less. Even more preferably, it is within the range of .2 or less. The X-ray diffraction spectrum of MSE type zeolite can be measured using an X-ray diffraction device (for example, model number: MiniFlex600, manufactured by Rigaku Co., Ltd.).

Method for producing MSE type zeolite MSE type zeolite is produced by preparing a raw material mixture containing a silica source, an aluminum source, an alkali metal source, an organic structure directing agent (template), and water, and heating and crystallizing this raw material mixture. and obtaining an MSE type zeolite.

As the silica source, for example, a compound containing silicon can be used. Specific examples include wet process silica, dry process silica, colloidal silica, sodium silicate, potassium silicate, aluminosilicate gel, and the like. These silica sources can be used alone or in combination of two or more. Among these silica sources, it is preferable to use silica (silicon dioxide), aluminosilicate gel, and colloidal silica because they are less likely to produce by-products and can produce the desired MSE type zeolite.

As the aluminum source, for example, a water-soluble aluminum-containing compound can be used. Specific examples include sodium aluminate, aluminum nitrate, aluminum sulfate, aluminum hydroxide, and aluminosilicate gel. These aluminum sources can be used alone or in combination of two or more. Among these aluminum sources, it is preferable to use sodium aluminate or aluminosilicate gel because they are less likely to produce by-products and the desired MSE type zeolite can be produced.

As the alkali metal source, for example, cesium hydroxide, potassium hydroxide, and sodium hydroxide can be used. In addition, when sodium silicate is used as a silica source or when sodium aluminate is used as an aluminum source, sodium, which is an alkali metal component contained therein, is also an alkali metal component. The alkali metal source is calculated as the sum of all alkali metal components in the reaction mixture.

Examples of the organic structure directing agent include those containing N,N,N',N'-tetraalkylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium ion. . The organic structure directing agent may be N,N,N',N'-tetraalkylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium iodide, The groups may be the same or different.

Step of Preparing a Raw Material Mixture When preparing a raw material mixture, the order of addition of each raw material may be such that a uniformly mixed raw material mixture can be easily obtained. For example, a uniformly mixed raw material mixture can be obtained by adding and dissolving an aluminum source in an alkali metal source that acts as a mineralizer at room temperature, then adding a silica source and stirring and mixing. The temperature at which the raw material mixture is prepared can generally be room temperature (20°C to 25°C).

Step of Crystallizing The raw material mixture can be crystallized by heating at a temperature of 70° C. or higher and 240° C. or lower. The heating performed on the raw material mixture is also referred to as first heating. The first heating may be performed by leaving the raw material mixture still, or may be performed while stirring the raw material mixture. The heating temperature may be 80°C or higher and 200°C or lower. The heating time may be 5 hours or more and 400 hours or less, 48 hours or more and 200 hours or less, or 72 hours or more and 80 hours or less. Heating may be performed under atmospheric pressure or under increased pressure.

Before heating, the raw material mixture may be allowed to stand for a certain period of time at a temperature lower than the heating temperature to age. Aging refers to holding the reaction mixture at the same temperature for a certain period of time at a temperature lower than the heating temperature during crystallization. The aging temperature may be from room temperature (20° C. to 25° C.) to 160° C., and the aging time may be from 2 hours to 160 hours.

After heating, the crystallized powder is separated from the mother liquor by filtration, washed with water or deionized water, and dried to obtain MSE type zeolite. The obtained MSE type zeolite is heated to remove organic substances remaining in the crystals. Heating for removing organic matter remaining in the crystal is also referred to as second heating. The second heating may be carried out at a temperature that can remove organic substances, and is preferably carried out at a temperature of 500°C or higher and 800°C or lower. In order to maintain the skeleton structure of the obtained MSE type zeolite, it is preferable to raise the temperature to the heating temperature over 2 hours or more, and the heating time to maintain the heating temperature after raising the temperature to the heating temperature is 0. It is preferable that the time is 5 hours or more and 3 hours or less.

The obtained MSE type zeolite can be confirmed to be an MSE type zeolite by measuring it using a powder X-ray diffractometer. In the X-ray diffraction spectrum using a powder X-ray diffractometer, 6.56 ± 0.15°, 6.8 ± 0.15°, 8.04 ± 0.15°, 19.38 ± 0.15°, 19.42±0.15°, 21.68±0.15°, 22.28±0.15°, 22.32±0.15°, 22.84±0.15°, 27.5°± If there is a diffraction peak at a diffraction angle (2θ) of 0.15°, it can be confirmed that the zeolite is an MSE type zeolite.

Method for producing EON type zeolite EON type zeolite is produced by preparing a raw material mixture containing a silica source, an aluminum source, an alkali metal source, water, and an organic structure directing agent (template) if necessary, and heating this raw material mixture. and a step of crystallizing to obtain EON type zeolite.

As the silica source, aluminum source, and alkali metal source, the same sources as those used in the above-described method for producing MSE type zeolite can be used.

Examples of the organic structure directing agent include those containing bis(2-hydroxyethyl)dimethylammonium ion and tris(2-hydroxyethyl)methylammonium. The organic structure directing agent may be bis(2-hydroxyethyl)dimethylammonium chloride or tris(2-hydroxyethyl)methylammonium hydroxide.

Step of preparing raw material mixture The raw material mixture can be prepared in the same manner as the method for producing MSE type zeolite described above.

Step of Crystallizing The raw material mixture can be crystallized by heating at a temperature of 70° C. or higher and 240° C. or lower. The heating performed on the raw material mixture is also referred to as first heating. The first heating may be performed by leaving the raw material mixture still, or may be performed while stirring the raw material mixture. The heating temperature may be 80°C or higher and 200°C or lower. The heating time may be 24 hours or more and 400 hours or less, 48 hours or more and 200 hours or less, or 72 hours or more and 170 hours or less. Heating may be performed under atmospheric pressure or under increased pressure.

Before heating, the raw material mixture may be allowed to stand for a certain period of time at a temperature lower than the heating temperature to age. Aging refers to holding the reaction mixture at the same temperature for a certain period of time at a temperature lower than the heating temperature during crystallization. The aging temperature may be from room temperature (20° C. to 25° C.) to 80° C., and the aging time may be from 2 hours to 80 hours.

After heating, the crystallized powder is separated from the mother liquor by filtration, washed with water or deionized water, and dried to obtain EON type zeolite. EON type zeolite synthesized using an organic structure directing agent is heated to remove organic matter remaining in the crystal. Heating for removing organic matter remaining in the crystal is also referred to as second heating. The second heating may be carried out at a temperature that can remove organic substances, and is preferably carried out at a temperature of 500°C or higher and 800°C or lower. Further, in order to maintain the skeleton structure of the obtained EON type zeolite, it is preferable to raise the temperature to the heating temperature over 2 hours or more, and the heating time to maintain the heating temperature after raising the temperature to the heating temperature is 0. Preferably, the time is 5 hours or more and 3 hours or less.

The obtained EON type zeolite can be confirmed to be an EON type zeolite by measuring it using a powder X-ray diffractometer. In the X-ray diffraction spectrum using a powder X-ray diffractometer, 6.42 ± 0.14°, 9.66 ± 0.15°, 13.02 ± 0.15°, 13.38 ± 0.15°, 23.12±0.15°, 25.44±0.15°, 26.18±0.15°, 27.56±0.15°, 27.78±0.16°, 28.06±0 If there is a diffraction peak at a diffraction angle (2θ) of .17°, it can be confirmed that it is EON type zeolite.

Method for incorporating metal into multipore zeolite Metal can be incorporated into multipore zeolite by a liquid phase ion exchange method, a solid phase ion exchange method, or an impregnation method. Examples of methods for incorporating metals include methods in which the metal is introduced into the multipore zeolite by ion exchange, and methods in which the surface of the multipore zeolite is modified in the form of an oxide. The liquid phase ion exchange method uses at least one metal selected from the group consisting of transition metals belonging to Groups 3 to 12 of the periodic table, amphoteric metals belonging to Groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals. This is a method of ion exchange by dispersing or immersing multipore zeolite in a solution of metal salts consisting of metal ions. The solid phase ion exchange method uses multipore zeolites and transition metals selected from the group consisting of transition metals belonging to groups 3 to 12 of the periodic table, amphoteric metals belonging to groups 13 and 14 of the periodic table, alkali metals and alkaline earth metals. In this method, metal salts or metal oxides containing at least one type of metal ion are mixed, and the mixture is heat-treated in a reducing atmosphere or an inert atmosphere at a temperature of, for example, 300° C. or higher and 800° C. or lower, thereby performing ion exchange. Examples of the metal salt include metal acetate, metal chloride, metal sulfate, metal nitrate, and the like. After the ion-exchange treatment, the ion-exchanged multipore zeolite is washed, dried at, for example, 100°C to 300°C, and then calcined at, for example, 400°C to 1000°C, so that the ion-exchanged sites on Al are ion-exchanged. Multipore zeolite can be obtained. The impregnation method uses at least one metal ion selected from the group consisting of transition metals belonging to Groups 3 to 12 of the periodic table, amphoteric metals belonging to Groups 13 and 14 of the periodic table, alkali metals, and alkaline earth metals. In this method, a multipore zeolite is immersed in a solution of a metal salt or metal oxide containing the zeolite, and dried by heat treatment at a temperature of, for example, 30° C. or higher and 200° C. or lower, thereby incorporating the metal. After drying, it is calcined at, for example, 400° C. to 1000° C. to obtain a multipore zeolite in which the ion exchange sites on Al are ion-exchanged. Examples of the metal salt include metal acetate, metal chloride, metal sulfate, metal nitrate, and the like. Examples of the impregnation method include an incipient wetness method, an evaporation to dryness method, a pore-filling method, a spray method, an equilibrium adsorption method, and the like. Examples of the precipitation method include a kneading method and a deposition method. The specific metal introduced into the multi-pore zeolite is at least partially incorporated into small pore cages (cages whose largest ring is no more than 8-membered), particularly cages with up to 8-membered rings or cages with up to 6-membered rings. Preferably, it is introduced. In order to introduce a specific metal into the cage of small pores, the firing temperature is preferably 450°C or higher, and the firing may be performed in an air atmosphere, under an inert atmosphere or under reduced pressure of 0.1 MPa or less. It is preferable to bake it in By introducing metal into the cage of small pores, large pores (pores with 10-membered rings or more) that adsorb hydrocarbons, especially tunnel-type (linear) pores with up to 12-membered rings and The volume of the 10-membered ring cage-shaped pore can be maintained. Furthermore, since specific metals do not interact directly with hydrocarbons, but instead act on the zeolite skeleton, multipore zeolites containing specific metals can adsorb hydrocarbons up to high temperatures.

The introduction of a specific metal into the small pore cages of multipore zeolite can be indirectly confirmed by changes in the zeolite's lattice constant through X-ray diffraction measurements. In addition, in multi-pore zeolite, the cage of small pores is The content of the specific metal introduced therein is preferably larger than 0.5, more preferably 1.0 or more, even more preferably 2.0 or more, in terms of molar ratio. It is particularly preferable that it is .0 or more. The content of specific metals in tunnel-type (linear) pores with a maximum of 12-membered rings, cage-type pores with a maximum of 10-membered rings, or cages of small pores can be determined by analysis using an X-ray diffraction device, etc. It can be determined indirectly from the change in the TO bond distance of the TO ₄ units forming the skeletal structure or the distance from the skeletal element.

Method for incorporating phosphorus or sulfur into multi-pore zeolite Phosphorus or sulfur can be incorporated into multi-pore zeolite by bringing the multi-pore zeolite into contact with a phosphorus-containing compound or a sulfur-containing compound. Examples of methods for incorporating phosphorus or sulfur into multipore zeolite include vapor deposition methods, impregnation methods, precipitation methods, and ion exchange methods. For the vapor deposition method, multi-pore zeolite and a phosphorus-containing compound or sulfur-containing compound are placed in a container, and the phosphorus or sulfur is evaporated at room temperature or by heating, so that the multi-pore zeolite contains phosphorus or sulfur. There are several methods. In the impregnation method, multi-pore zeolite is immersed in a liquid mixture of a phosphorus-containing compound or a sulfur-containing compound and a solvent, and the mixed liquid is heated and dried under normal pressure or reduced pressure to impregnate phosphorus or sulfur. An example is a method of incorporating it into poiseolite. Here, the phosphorus-containing compound may be phosphorus or an ion containing phosphorus. Further, the sulfur-containing compound may be sulfur or an ion containing sulfur. Examples of the impregnation method include an incipient wetness method, an evaporation to dryness method, a pore-filling method, a spray method, an equilibrium adsorption method, and the like. Examples of the precipitation method include a kneading method and a deposition method.

When phosphorus is contained in the multipore zeolite by a vapor deposition method, examples of the phosphorus-containing compound include trimethyl phosphate, triethyl phosphate, trimethyl phosphite, and triethyl phosphite. Trimethyl phosphate is preferred because of its low boiling point. When phosphorus is contained in multipore zeolite by an impregnation method, the phosphorus-containing compound is preferably water-soluble, such as trimethyl phosphate, triethyl phosphate, trimethyl phosphite, triethyl phosphite, phosphoric acid, etc. , dihydrogen phosphates such as ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, and hydrogen phosphates such as diammonium hydrogen phosphate and dipotassium hydrogen phosphate. Examples of phosphoric acid include orthophosphoric acid (H ₃ PO ₄ ), pyrophosphoric acid (H ₄ P ₂ O ₇ ), triphosphoric acid (H ₅ P ₃ O ₁₀ ), polyphosphoric acid, metaphosphoric acid (HPO ₃ ), ultraphosphoric acid, etc. can be mentioned. From the viewpoint of easy drying, phosphoric acid such as orthophosphoric acid, trimethyl phosphate, ammonium dihydrogen phosphate, or ammonium phosphate such as diammonium hydrogen phosphate is preferred. Examples of the solvent to be mixed with the phosphorus-containing compound include polar organic solvents such as deionized water, ethanol, 2-propanol, and acetone. It is preferable to use deionized water and ethanol because they are easy to handle and dry. The phosphorus-containing compound may be in the range of 1% by mass or more and 25% by mass or less, and may be in the range of 2% by mass or more and 20% by mass or less, with respect to 100% by mass of the total amount of the mixed liquid. It may be within the range of 5% by mass or more and 15% by mass or less. When a phosphorus-containing compound is attached to multipore zeolite by an impregnation method, the time for impregnating the multipore zeolite in the mixed liquid can be 0.5 hours or more and 2 hours or less. After impregnation, the multipore zeolite containing the phosphorus-containing compound may be dried, and the drying temperature may be 80°C or more and 200°C or less, and the drying time may be 0.5 hours or more and 5 hours or less. can. Further, the pressure during drying is not particularly limited, and may be atmospheric pressure (0.1 MPa) or may be under reduced pressure of 0.1 MPa or less. When incorporating sulfur into the multipore zeolite, it is preferable to use sulfate.

After a compound containing phosphorus or sulfur is attached to multipore zeolite by a vapor deposition method or an impregnation method, it is heat-treated to obtain a multipore zeolite containing phosphorus or sulfur. The heat treatment temperature is preferably in the range of 200°C or more and 800°C or less, more preferably 400°C or more and 700°C or less, in order to maintain the skeletal structure of the multipore zeolite. The atmosphere for the heat treatment may be an air atmosphere or an inert gas atmosphere such as nitrogen.

Multipore zeolites containing certain metals can be used as hydrocarbon adsorbents. In the exhaust gas purification catalyst described below, the hydrocarbon adsorbent constituting the hydrocarbon adsorption section is not only multi-pore zeolite containing a specific metal, but also BEA type (zeolite with only 12-membered rings) and MTW type (12-membered ring zeolite). Non-multipore zeolites such as ring-only zeolites) may also be included. For example, MSE type zeolite, which is a multipore zeolite, may include MOR type zeolite, which is a multipore zeolite, BEA type zeolite, which is a non-multipore zeolite, and MTW type zeolite, which is a non-multipore zeolite. The hydrocarbon adsorbent may consist of 100% by mass of multipore zeolites containing specific metals, and in addition to multipore zeolites containing specific metals, non-multipore zeolites such as BEA type and MTW type may be used. When containing pore zeolite, the content of multipore zeolite containing a specific metal is preferably within the range of 50% by mass to 99% by mass, and 80% by mass in 100% by mass of the hydrocarbon adsorbent. It is more preferably in the range of 99% by mass or less, and even more preferably in the range of 90% by mass or more and 99% by mass or less.

A hydrocarbon adsorbent made of multi-pore zeolite containing a specific metal can be used as an exhaust gas purification catalyst by combining a hydrocarbon adsorption section containing this hydrocarbon adsorption material and a purification catalyst section. A hydrocarbon adsorption material made of multi-pore zeolite containing a specific metal element can be used to form a hydrocarbon adsorption part by producing a composition for a hydrocarbon adsorption part containing this hydrocarbon adsorption material.

Exhaust Gas Purification Catalyst A first example of the embodiment of the present invention includes a base material, a hydrocarbon adsorption section including the hydrocarbon adsorption material on the base material, and a purification catalyst section on the hydrocarbon adsorption section. It is also an exhaust gas purification catalyst.

1 and 2 show an example of an exhaust gas purification catalyst 10. FIG. 1 shows a base material 1 made of ceramics, and the base material 1 has a plurality of cells 1a and partition walls 1b that partition the cells 1a. FIG. 2 shows a part of a cross section of the exhaust gas purification catalyst of the first example. A purification catalyst section 3 is provided on the catalytic converter 2. In FIG. 2, reference numeral 30 is an exhaust gas flow path.

The purification catalyst section 3 of the first example includes a first purification catalyst section 3a that contains at least one kind of Rh and Pt and has a Pd content of 0.1% by mass or less, and a first purification catalyst section 3a that contains at least one kind of Rh and Pt, and a first purification catalyst section 3a that contains at least one kind of Pd and Pd. and a Rh content of 0.1% by mass or less, the first purification catalyst part 3a is disposed on the hydrocarbon adsorption part 2 side, and the first purification catalyst part 3a A second purification catalyst section 3b may be provided above.

Preferably, the first purification catalyst section contains a cerium oxide-zirconium oxide composite oxide (CeO ₂ -ZrO ₂ ). The content of CeO ₂ in the cerium oxide-zirconium oxide composite oxide is preferably more than 0% by mass and not more than 30% by mass, more preferably in the range of 15% by mass or more and not more than 30% by mass. When the first purification catalyst section contains cerium oxide-zirconium oxide with a CeO ₂ content of 15% by mass or more and 30% by mass or less, hydrocarbons desorbed from the hydrocarbon adsorption section can be directly oxidized. preferable.

A second example of the embodiment of the present invention includes a base material, a hydrocarbon adsorbent on the base material, and at least one of Rh and Pt, and the content of Pd is 0.1% by mass or less. An exhaust gas purification catalyst comprising a hydrocarbon adsorption part and a purification catalyst part containing at least one of Pd and Pt on the hydrocarbon adsorption part and having an Rh content of 0.1% by mass or less. .

FIG. 3 shows a part of a cross section of the second example of the exhaust gas purification catalyst, and the exhaust gas purification catalyst 10 includes a base material 1, a hydrocarbon adsorption section 2 provided on the base material 1, and a hydrocarbon adsorption section provided on the base material 1. A purification catalyst section 3 is provided on the catalytic converter 2. In FIG. 3, numeral 30 is an exhaust gas flow path.

Each part constituting the exhaust gas purification catalyst will be explained below.

Base Material As the base material, a known exhaust gas catalyst base material can be used. Examples of the material of the base material include ceramics and metal. Examples of the ceramic base material include refractory ceramic materials such as cordierite, hydrocarbon, mullite, silica-alumina, and alumina. Examples of the metal base material include refractory metals such as stainless steel. Further, as for the shape of the base material, for example, a base material having a shape such as a honeycomb-shaped base material having a large number of parallel cells serving as fine flow paths inside the base material can be used. Examples of the shape of such a base material include a wall flow type base material and a flow-through type base material.

Hydrocarbon adsorption section The hydrocarbon adsorption section consists of a hydrocarbon adsorbent containing a multi-pore zeolite containing the above-mentioned metals or a hydrocarbon adsorption material consisting of a multi-pore zeolite containing the above-mentioned metals, alumina particles, an oxygen absorbing/releasing material, and an alumina sol. A slurry-like composition for a hydrocarbon adsorption part containing an inorganic oxide such as silica sol, zirconia sol, etc. is prepared, and this slurry-like composition for a hydrocarbon adsorption part is applied to a base material, and dried as necessary. The hydrocarbon adsorbing portion can be formed by baking this. Examples of the oxygen absorbing/releasing material include inorganic oxides such as ceria-zirconia composite oxide. The inorganic oxide may contain rare earth elements. The hydrocarbon adsorption part composition for forming the hydrocarbon adsorption part may contain Rh and/or Pt. When the hydrocarbon adsorbent contained in the composition for the hydrocarbon adsorption section is a hydrocarbon adsorption material made of MSE type zeolite among multipore zeolites, the content of the hydrocarbon adsorption material is equal to the composition for the hydrocarbon adsorption section. Based on the solid content of the product, it is preferably 10% by mass or more and 85% by mass or less, more preferably 50% by mass or more and 75% by mass or less, and further preferably 60% by mass or more and 70% by mass or less. preferable. When the hydrocarbon adsorption part contains Rh and/or Pt, the total content of Rh and Pt contained in the hydrocarbon adsorption part is 0.0% relative to the solid content of the composition for the hydrocarbon adsorption part. It is preferably 0.05% by mass or more and 0.8% by mass or less, more preferably 0.14% by mass or more and 0.7% by mass or less, and 0.2% by mass or more and 0.5% by mass or less. is even more preferable. By containing Rh and/or Pt in the hydrocarbon adsorption section, hydrocarbons desorbed within the hydrocarbon adsorption section can be effectively purified.

For the purification catalyst part, prepare a slurry-like composition for the purification catalyst part, apply this slurry-like composition for the exhaust gas purification catalyst part on the hydrocarbon adsorption part formed on the base material, and apply it as necessary. The purification catalyst section can be formed by drying the catalyst and firing it. A slurry-like composition for a purification catalyst part can be produced by mixing and stirring an element serving as a catalytically active component, a NOx storage material, a catalyst carrier, a stabilizer as necessary, a binder, other components, and water. As the binder, an inorganic binder such as an aqueous solution such as alumina sol can be used. When the exhaust gas purification catalyst includes each layer of an oxidation catalyst layer, a NOx storage layer, and a reduction catalyst layer, the composition for the exhaust gas purification catalyst part constituting each layer contains a catalytically active element necessary for the catalytic activity of each layer. A composition for the catalyst part can be used.

The purification catalyst section includes a first purification catalyst section containing Rh and a second purification catalyst section containing Pd, the first purification catalyst section being disposed on the hydrocarbon adsorption section side and above the first purification catalyst section. In the case where a second purification catalyst part is provided, a composition for the first purification catalyst part containing Rh and a composition for the second purification catalyst part containing Pd are prepared. Furthermore, when the hydrocarbon adsorption section contains the above-mentioned hydrocarbon adsorption material and Rh, a composition for the purification catalyst section containing Pd is prepared.

The first purification catalyst composition contains Rh and/or Pt. The total content of Rh and Pt in the composition for the first purification catalyst part is 0.1% by mass or more and 1.8% by mass or less based on the solid content of the composition for the first purification catalyst part. It is preferably 0.2% by mass or more and 1.2% by mass or less, and even more preferably 0.5% by mass or more and 1.0% by mass or less.
The composition for the first catalyst part is a cerium oxide-zirconium oxide composite oxide having a CeO ₂ content of preferably more than 0% by mass and 30% by mass or less, more preferably 15% by mass or more and 30% by mass or less. (CeO ₂ -ZrO ₂ ) is preferably included. In this specification, a cerium oxide-zirconium oxide composite oxide in which the content of CeO ₂ is in the range of 15% by mass or more and 30% by mass and contains more ZrO ₂ than CeO ₂ is referred to as "ZC composite oxide". ” is also called. The content of the ZC composite oxide in the composition for the first catalyst part is preferably 30% by mass or more and 80% by mass or less, and 50% by mass, based on the solid content of the composition for the first purification catalyst part. It is more preferably 80% by mass or less, and even more preferably 55% by mass or more and 75% by mass or less.
The composition for the first purification catalyst portion may contain a platinum group metal other than Rh and Pt. The content of platinum group metals other than Rh and Pt in the composition for the first catalyst part is less than 50% by mass with respect to the total amount of platinum group metals contained in the composition for the first purification catalyst part. It is preferable that there be. Preferably, the composition for the first purification catalyst section does not substantially contain Pd. "Substantially not containing Pd in the composition for the first catalyst section" means that when Pd is contained in the solid content of the composition for the first catalyst section, it is less than 0.1 mass, It is preferable that Pd be 0% by mass based on the solid content of the composition for the first catalyst part. Platinum group metals refer to Pt, Pd, Rh, Ir, Ru, and Os.

The composition for the second purification catalyst part or the composition for the purification catalyst part contains Pd and/or Pt. The total content of Pd and Pt in the composition for the second purification catalyst part shall be 0.5% by mass or more and 8.0% by mass or less based on the solid content of the composition for the second purification catalyst part. It is preferably 0.8% by mass or more and 7.0% by mass or less, and even more preferably 1.5% by mass or more and 3.5% by mass or less.
The composition for the second purification catalyst section preferably contains a cerium oxide-zirconium oxide composite oxide (CeO ₂ -ZrO ₂ ) having a CeO ₂ content in the range of 25% by mass to 55% by mass. In this specification, a cerium oxide-zirconium oxide composite oxide in which the content of CeO ₂ is within the range of 25% by mass to 55% by mass and contains less ZrO ₂ than CeO ₂ is referred to as a "CZ composite oxide". Also called. The content of the CZ composite oxide in the composition for the second purification catalyst part is preferably 20% by mass or more and 80% by mass or less, and 30% by mass, based on the solid content of the composition for the second purification catalyst part. It is more preferably 70% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less.
The composition for the second purification catalyst portion may contain a platinum group metal other than Pd and Pt. The content of platinum group metals other than Pd and Pt in the composition for the second purification catalyst part is less than 50% by mass with respect to the total amount of platinum group metals contained in the composition for the second purification catalyst part. It is preferable that there be.
It is preferable that the composition for the second purification catalyst part or the composition for the purification catalyst part does not substantially contain Rh. "Substantially not containing Rh in the composition for the second purification catalyst section" means that if Rh is contained in the solid content of the composition for the second purification catalyst section, it is less than 0.1% by mass. It is preferable that Rh is 0% by mass based on the solid content of the composition for the second purification catalyst part.

The composition for the purification catalyst part, the composition for the first purification part, or the composition for the second purification catalyst part can be produced by any known means. For example, a compound containing a specific element such as Rh, Pt or Pd is brought into contact with an inorganic oxide carrier (for example, a cerium oxide-zirconium oxide composite oxide) to obtain an inorganic oxide carrier on which the specific element is supported, A composition for a purification catalyst section containing this inorganic oxide carrier may also be used. Examples of the method for attaching the specific element to the inorganic oxide carrier include a vapor deposition method, an impregnation method, a precipitation method, and an ion exchange method. Examples of the vapor deposition method include a method in which an inorganic oxide or a compound containing a specific element is placed in a container, and the compound containing the element is evaporated at room temperature or heated to adhere to the inorganic oxide. In the impregnation method, an inorganic oxide is immersed in a liquid mixture of a compound containing the above element and a solvent, and the mixed liquid is heated and dried under normal pressure or reduced pressure to convert the compound containing the above element into the inorganic oxide. An example of this method is to attach it. Examples of the impregnation method include an incipient wetness method, an evaporation to dryness method, a pore-filling method, a spray method, an equilibrium adsorption method, and the like. Examples of the precipitation method include a kneading method and a deposition method. The zeolite to which the compound containing the above element is attached may be dried at a temperature of, for example, 80° C. or higher and 150° C. or lower, the drying time is 0.5 hours or more and 5 hours or less, and the pressure during drying is: There is no particular restriction, and the pressure may be atmospheric pressure (0.1 MPa) or may be under reduced pressure of 0.1 MPa or less. The zeolite to which the above elements have been attached may be dried and further subjected to heat treatment, if necessary. The heat treatment temperature may be in the range of 200°C or more and 800°C or less, or may be in the range of 400°C or more and 700°C or less, in order to prevent damage to the pores of the zeolite.

In the case of the exhaust gas purification catalyst of the first example, the purification catalyst section includes a first purification catalyst section containing at least one kind of Rh and Pt, and a second purification catalyst section containing at least one kind of Pd and Pt, A first purification catalyst part composition may be applied on the hydrocarbon adsorption part formed on the base material, dried if necessary, and fired to form the first purification catalyst part. can. Next, a second purification catalyst part composition can be applied onto the first purification catalyst part, dried if necessary, and fired to form a second purification catalyst part. The first purification catalyst section and the second purification catalyst section can be determined by quantitatively analyzing a cross section of the exhaust gas purification catalyst using an electron probe micro analyzer (EPMA). The platinum group metals contained in the first purification catalyst portion are mainly Rh and Pt, and Pd is not substantially contained. The first purification catalyst part has a Pd content of 0.1% by mass relative to 100% by mass of the solid content of the composition for the first catalyst part when a cross section of the exhaust gas purification catalyst is quantitatively analyzed by EPMA. Refers to parts that are: The platinum group metals contained in the second purification catalyst portion are mainly Pd and Pt, and substantially no Rh is contained. In the second purification catalyst part, when a cross section of the exhaust gas purification catalyst was quantitatively analyzed by EPMA, the Rh content was 0.1% by mass based on 100% by mass of the solid content of the composition for the second catalyst part. Refers to parts that are:

In the case of the second example of the exhaust gas purification catalyst in which the hydrocarbon adsorption part includes a hydrocarbon adsorbent and Rh, a purification catalyst composition containing Pd is coated on the hydrocarbon adsorption part formed on the base material. Then, if necessary, it can be dried and fired to form a purification catalyst section. The purification catalyst section can be determined by quantitatively analyzing a cross section of the exhaust gas purification catalyst using an electron probe micro analyzer (EPMA). The platinum group metals contained in the purification catalyst portion are mainly Pd and Pt, and substantially no Rh is contained. The purification catalyst part refers to a part where Rh is 0.1% by mass or less based on 100% by mass of the solid content of the composition for the purification catalyst part, when a cross section of the exhaust gas purification catalyst is quantitatively analyzed by EPMA. .

Exhaust gas purification catalysts can also be used in selective catalytic reduction (SCR) systems. Selective catalytic reduction (SCR) can reduce NOx to _N2 by reacting with nitrogen compounds or hydrocarbons such as ammonia or urea.

Exhaust gas purification catalysts can be used to purify the exhaust gas of internal combustion engines powered by fuel, such as gasoline engines and diesel engines, and can adsorb and store hydrocarbons up to relatively high temperatures. The removal performance and NOx reduction performance can be improved.

Exhaust Gas Purification System An exhaust gas purification system using the above-mentioned exhaust gas purification catalyst will be explained.
4 to 6 show exhaust gas purification systems of first to third examples of the present invention.

As shown in FIG. 4, the exhaust gas purification system 100 of the first example includes an internal combustion engine 20, a first exhaust gas purification catalyst 40 provided upstream in an exhaust gas flow path 30 connected to the internal combustion engine, and an exhaust gas flow A second exhaust gas purification catalyst 10 is provided in the passage 30 on the downstream side of the first exhaust gas purification catalyst 40 in the exhaust gas flow direction. The second exhaust gas purification catalyst 10 is the exhaust gas purification catalyst 10 of the first or second example of the present invention described above. When the second exhaust gas purification catalyst 10 is provided downstream in the exhaust gas flow path 30 than the first exhaust gas purification catalyst, the exhaust gas at a relatively high temperature of about 1000° C. discharged from the internal combustion engine 10 is Since the temperature of the exhaust gas decreases after passing through the first exhaust gas purification catalyst 40, it is possible to suppress the deterioration of the multipore zeolite contained in the hydrocarbon adsorption section of the second exhaust gas purification catalyst due to heat, and the Adsorption ability can be maintained. The second exhaust gas purification catalyst 10, which is the aforementioned exhaust gas purification catalyst, has a platinum group content within a range of 0.1 g/L or more and 3.0 g/L or less based on the volume of the second exhaust gas purification catalyst. . The content ratio of the platinum group metal in the second exhaust gas purification catalyst 10, which is the aforementioned exhaust gas purification catalyst, is within the range of 0.1 g/L or more and 3.0 g/L or less with respect to the volume of the second exhaust gas purification catalyst. If there is, the desorbed hydrocarbons can be purified more efficiently. Although FIG. 4 shows an example in which there are two exhaust gas purification catalysts, the first exhaust gas purification catalyst 40 and the second exhaust gas purification catalyst 10, there may be three or more exhaust gas purification catalysts. For example, another exhaust gas purification catalyst may be provided downstream of the second exhaust gas purification catalyst 10 in the exhaust gas flow direction. Other exhaust gas purification catalysts provided downstream of the second exhaust gas purification catalyst 10 may be the exhaust gas purification catalyst 10 of the first or second example of the present invention described above, or other exhaust gas purification catalysts may be used. It may also be a catalyst. Other shapes of the base material used in the exhaust gas purification catalyst include a wall flow type base material, a flow-through type base material, etc. as appropriate.

As shown in FIG. 5, the exhaust gas purification system 200 of the second example includes an internal combustion engine 20 and a single exhaust gas purification catalyst 10 provided in an exhaust gas passage 30 connected to the internal combustion engine. The purification catalyst 10 is the aforementioned exhaust gas purification catalyst of the present invention. Since the exhaust gas purification system 200 of the second example of the present invention includes the exhaust gas purification catalyst 10 of the present invention which has high hydrocarbon removal performance, the exhaust gas purification system 200 has high exhaust gas purification performance when applied to an internal combustion engine with a relatively small displacement. Since the number of exhaust gas purification catalysts 10 can be set to one while being sufficient, it is possible to achieve both high purification performance and low cost.

As shown in FIG. 6, the exhaust gas purification system 300 of the third example includes an internal combustion engine 20 and a plurality of exhaust gas purification catalysts 10, 50, 60 in an exhaust gas passage 30 connected to the internal combustion engine. Among the exhaust gas purification catalysts 10, 50, and 60, the first exhaust gas purification catalyst 10 disposed on the most upstream side in the exhaust gas flow direction is the exhaust gas purification catalyst of the present invention described above. In the exhaust gas purification system 300 of the third example shown in FIG. An example is shown. The exhaust gas purification system 300 only needs to include two or more exhaust gas purification catalysts in the exhaust gas flow path 30, and the number of exhaust gas purification catalysts is not limited. The exhaust gas purification system 300 of the third example of the present invention includes a plurality of exhaust gas purification catalysts in the exhaust gas flow path 30, and the first exhaust gas purification catalyst 10 disposed on the most upstream side is the exhaust gas purification catalyst of the present invention. , the desorbed hydrocarbons can be purified more efficiently by the downstream exhaust gas purification catalyst.

Method for Treating Exhaust Gas A method for treating exhaust gas according to an embodiment of the present invention includes bringing a combustion exhaust gas containing hydrocarbons into contact with an exhaust gas purification catalyst according to an embodiment of the present invention, to remove hydrocarbons. The method includes adsorbing hydrocarbons on the exhaust gas purification catalyst and then desorbing the hydrocarbons from the exhaust gas purification catalyst at a temperature of 200° C. or higher.

Hereinafter, the present invention will be further explained in detail based on Examples and Comparative Examples. The present invention is not limited to these examples.

Production of MSE type zeolite Deionized water (pure water), potassium hydroxide, aluminum hydroxide, N,N,N',N'-tetraalkylbicyclo[2.2.2]oct-7-ene-2 iodide , 3:5,6-dipyrrolidinium, and colloidal silica (LUDOX (registered trademark) HS-40, manufactured by Sigma-Aldrich Japan Co., Ltd.) were prepared and mixed, so that the molar ratio of each raw material was as follows. A raw material composition was obtained.
SiO ₂ /Al ₂ O ₃ =20
K/Si=0.38
N,N,N',N'-tetraalkylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium iodide/Si=0.1
_H2O /Si=30

The obtained raw material composition was filled into a closed container, left standing, and heated at 160° C. for 16 days to crystallize it. The raw material composition after crystallization was subjected to solid-liquid separation, washed with deionized water, and crystals were collected. The obtained crystals were dried at 100°C for 8 hours and heat treated at 600°C for 1 hour in the air to obtain MSE type zeolite. It was confirmed that the obtained zeolite was of the MSE type by measurement using a powder X-ray diffractometer. In the X-ray diffraction spectrum using a powder X-ray diffractometer, if there is a diffraction peak at the above-mentioned diffraction angle (2θ) position, it can be confirmed that the zeolite is MSE type zeolite. The diffraction angle (2θ) position of the diffraction peak in the X-ray diffraction spectrum is the same as the diffraction angle (2θ) position of the diffraction peak in the X-ray diffraction spectrum published by the International Zeolite Society. FIG. 7 shows the X-ray diffraction spectrum of the obtained MSE type zeolite.
The obtained MSE type zeolite had a composition in which the molar ratio of each component was as follows.
SiO ₂ /Al ₂ O ₃ =20

Production of EON-type zeolite Prepare deionized water (pure water), sodium hydroxide, sodium aluminate, and No. 3 sodium silicate, and mix them to produce raw materials with the following molar ratio of each raw material. A composition was obtained.
_SiO2 / _{Al2O3 =} 10
Na/Si=0.44
_H2O /Si=20

The obtained raw material composition was filled into a closed container, left standing, and heated at 150° C. for 7 days to crystallize it. The raw material composition after crystallization was subjected to solid-liquid separation, washed with deionized water, and crystals were collected. The obtained crystals were dried at 100° C. for 8 hours and heat treated at 600° C. for 1 hour in an air atmosphere to obtain EON type zeolite. It was confirmed that the obtained zeolite was of the EON type by measurement using a powder X-ray diffractometer. In the X-ray diffraction spectrum using a powder X-ray diffractometer, if there is a diffraction peak at the above-mentioned diffraction angle (2θ) position, it can be confirmed that the zeolite is an EON type zeolite. The diffraction angle (2θ) position of the diffraction peak in the X-ray diffraction spectrum is the same as the diffraction angle (2θ) position of the diffraction peak in the X-ray diffraction spectrum published by the International Zeolite Society. FIG. 8 shows the X-ray diffraction spectrum of the obtained EON type zeolite.
The obtained EON type zeolite had a composition in which the molar ratio of each component was as follows.
SiO ₂ /Al ₂ O ₃ =7.6
Na/Al=0.95

Example 1
Production of hydrocarbon adsorbent 1 g of the obtained MSE type zeolite was immersed in 10 g of 1 mol/L ammonium chloride aqueous solution at 80°C, separated into solid and liquid, and washed with deionized water to obtain NH ₄ type MSE type zeolite. Ta. 1 g of the obtained NH ₄ type MSE type zeolite was immersed in 100 g of a 0.25 mol/L copper acetate aqueous solution at 60° C., solid-liquid separation was performed, and the wet powder was recovered by washing with deionized water. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =20
Cu/Al=0.75

Example 2
1 g of the obtained MSE type zeolite was immersed in 10 g of 1 mol/L ammonium chloride aqueous solution at 80°C, solid-liquid separation was performed, and washed with deionized water to obtain an NH ₄ type MSE type zeolite. 1 g of the obtained _NH4 type MSE type zeolite was immersed in 100 g of a 0.25 mol/L cesium chloride aqueous solution, solid-liquid separation was performed, and washed with deionized water to obtain a Cs type MSE type zeolite in a wet state. . The obtained Cs-containing MSE type zeolite was dried at 100°C for 8 hours and heat treated at 550°C for 3 hours in the air. As a result, a Cs ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The MSE type zeolite was ion-exchanged with Cs and H. The obtained MSE type zeolite containing Cs was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =20
Cs/Al=0.22

Example 3
1 g of the obtained EON type zeolite was immersed in 10 g of 1 mol/L ammonium chloride aqueous solution at 60°C, solid-liquid separation was performed, and washed with deionized water to obtain an NH ₄ type EON type zeolite. 1 g of the obtained _NH4 type EON type zeolite was immersed in 2.5 g of 1 mol/L sulfuric acid at 60°C, separated into solid and liquid, and washed with deionized water to obtain H type EON type zeolite. 1 g of the obtained H-type EON-type zeolite was immersed in 10 g of a 0.50 mol/L copper (II) acetate aqueous solution, separated into solid and liquid, washed with deionized water, and a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged EON type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion-exchanged EON type zeolite was used as a hydrocarbon adsorbent.
_SiO2 / _Al2O3 = ₂₀
Cu/Al=0.5

Example 4
1 g of wet powder of H-type EON-type zeolite obtained in Example 3 described above was immersed in 5.0 g of a 0.30 mol/L cesium carbonate aqueous solution at 60°C, separated into solid and liquid, and washed with deionized water. , a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cs ion-exchanged EON type zeolite having a composition with the following molar ratio was obtained. The obtained Cs ion exchange EON type zeolite was used as a hydrocarbon adsorbent.
_SiO2 / _Al2O3 = ₁₃
Cs/Al=0.25

Comparative example 1
1 g of commercially available H-type BEA-type zeolite (SiO ₂ /Al ₂ O ₃ molar ratio = 37) was suspended in 5 g of copper (II) acetate aqueous solution at 60° C., and a wet powder was recovered by evaporation to dryness. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu-containing BEA type zeolite having a composition with the following molar ratio was obtained. The obtained BEA type zeolite containing Cu was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =37
Cu/Al=0.88

Comparative example 2
1 g of BEA type zeolite (SiO ₂ /Al ₂ O ₃ molar ratio = 37) was immersed in 10 g of 0.1 mol/L ammonium chloride aqueous solution at 60°C, separated into solid and liquid, washed with deionized water, and converted into NH ₄ type zeolite. BEA type zeolite was obtained. 1 g of the obtained NH ₄ type BEA type zeolite was immersed in 30 g of a 0.05 mol/L cesium acetate aqueous solution at 60° C., separated into solid and liquid, washed with deionized water, and a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cs-containing BEA type zeolite having a composition with the following molar ratio was obtained. The MSE type zeolite was ion-exchanged with Cs and H. The obtained BEA type zeolite containing Cs was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =37
Cs/Al=0.18

Comparative example 3
An MFI type zeolite containing Cs was obtained in the same manner as in Comparative Example 3, except that MFI type zeolite (SiO ₂ /Al ₂ O ₃ molar ratio = 39) was used instead of BEA type zeolite. The MSE type zeolite was ion-exchanged with Cs and H. The composition of the MFI type zeolite containing Cs was as follows in the molar ratio. The obtained MFI type zeolite containing Cs was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =39
Cs/Al=0.17

Comparative example 4
The wet powder of the NH ₄ type MSE type zeolite obtained in Example 1 described above was dried at 100°C for 8 hours, heat-treated at 550°C for 3 hours in the air, and used as a hydrocarbon adsorbent as it was.

Preparation of measurement sample The raw material composition or each zeolite was filled into a vinyl chloride tube with a diameter of 30 mm, and compression molded to prepare a measurement sample.

SiO ₂ /Al ₂ O ₃ molar ratio The Si amount and Al amount in the measurement sample were measured by elemental analysis using a scanning fluorescent X-ray analyzer (ZSX Primus II, manufactured by Rigaku Corporation), and the measured Si amount and Al amount were determined by elemental analysis. The SiO ₂ /Al ₂ O ₃ ratio was calculated from the amount.

Cu/Al Ratio The amount of Cu and the amount of Al in the measurement sample were measured by elemental analysis using the above-mentioned scanning fluorescent X-ray analyzer, and the amount of Cu and Cu/Al were calculated. In Table 1, the amount of Cu is described as the metal content ratio, and the Cu/Al is described as the metal/Al ratio.

Cs/Al Ratio Using the above-mentioned scanning fluorescent X-ray analyzer, the amount of Cs and the amount of Al in the measurement sample were measured by elemental analysis, and Cs/Al was calculated. In Table 1, the Cs amount is described as the metal content ratio, and the Cs/Al is described as the metal/Al ratio.

Desorption amount/adsorption amount of toluene Each of the hydrocarbon adsorbents of Examples and Comparative Examples was heated from 50°C to 500°C by a temperature raising reaction method while flowing toluene, and the adsorption temperature, desorption temperature, and adsorption temperature of toluene were measured. The amount and amount of desorption were measured.
Specifically, 0.1 g of a measurement sample of each hydrocarbon adsorbent was filled into a quartz reaction tube of a flow reactor, and a fixed bed flow reactor was used as the flow reactor to prepare an evaluation gas containing 71 ppm of toluene. While flowing at a rate of 1 L/min, the temperature was raised from 50°C to 500°C at a rate of 20°C/min using a temperature rising reaction method, and toluene was adsorbed and desorbed. To measure the adsorption and desorption of toluene on zeolite, the decrease in the amount detected by a downstream detector (VMS-1000F, manufactured by Shimadzu Corporation) with respect to the flow rate of toluene was used as the adsorption amount and purification amount. In areas where a value greater than the flow rate to the hydrocarbon adsorbent is detected, adsorbed hydrocarbons have been desorbed. The ratio of the total molar amount ZD ₂ desorbed from the hydrocarbon adsorbent at 200° C. or lower to the total molar amount ZD ₁ of toluene adsorbed at 50° C. or higher and lower than 200° C. (ZD ₂ /ZD ₁ × 100) is calculated as the ratio of toluene desorption. It was defined as the amount of separation/amount of adsorption. The results are shown in Table 1.
Gas for evaluation of measurement conditions: 71 ppm of toluene, the balance being nitrogen (N ₂ ).

Heat Treatment Each of the hydrocarbon adsorbents of Examples 1, 2, and 4 and Comparative Examples 1 to 4 was heat treated under the following conditions.
(1) Temperature: 850℃
(2) Time: 25 hours (3) Atmosphere: Atmosphere containing 10 volume % water vapor (H ₂ O), vaporize water vapor from a water tank, adjust the saturated water vapor pressure depending on the temperature, and create 10 volume % water vapor. The atmosphere shall be one containing:
(4) Model gas distribution mode: The model gas in (5) below is alternately circulated at 3 L/min for 80 seconds and Air at 3 L/min for 20 seconds.
(5) Model gas: The total of C ₃ H ₆ , O ₂ and N ₂ is 3 L/min, C ₃ H ₆ is 70 mL/min, O ₂ is 70 mL/min, and the balance is nitrogen (N ₂ ). .

Peak intensity ratio of X-ray diffraction spectrum The hydrocarbon adsorbents of Examples 1, 2, 4 and Comparative Examples 1 to 4 before and after heat treatment were measured using an X-ray diffraction device (model number: MiniFlex600, manufactured by Rigaku Corporation), The peak intensity ratio of the X-ray diffraction spectra before and after the heat treatment was determined using the following formula. The diffraction angle (2θ) position of the diffraction peak for determining the peak intensity ratio is the strongest peak near 2θ = 21.7° for MSE type zeolite, the strongest peak near 2θ = 22.4° for BEA type zeolite, The MFI type zeolite had the strongest peak around 2θ = 22.9°, and the EON type zeolite had the strongest peak around 2θ = 25.6°. The higher the calculated peak intensity ratio, the more the zeolite maintains its crystal structure even after heat treatment.
Peak intensity ratio (%) = (Peak intensity after heat treatment/Peak intensity before heat treatment) x 100

As shown in Table 1, the hydrocarbon adsorbents of Examples 1 to 4 (multipore zeolites containing specific metals) have a higher desorption/adsorption amount of toluene than zeolites of Comparative Examples 2 to 4. has a low value, that is, the amount of desorption is small compared to the amount of adsorption, and toluene can be stored up to a temperature of about 200°C, and toluene can be removed from the hydrocarbon adsorbent at a relatively high temperature of 200°C or higher. It was confirmed that it was possible to remove the In addition, the hydrocarbon adsorbents of Examples 1, 2, and 4 have a higher peak intensity ratio in their X-ray diffraction spectra than the zeolite of Comparative Example 1, and their crystals are maintained even after heat treatment, indicating that they have excellent heat resistance. was confirmed. Note that zeolite generally has a low skeleton density (total amount of Si and Al per unit volume), and the greater the amount of metal introduced, the lower the heat resistance. On the other hand, MSE type zeolite or EON type zeolite, which are multipore zeolites, have a higher skeletal density than BEA type zeolite and MFI type zeolite, and therefore are considered to have better heat resistance. Although the peak intensity ratio of the hydrocarbon adsorbent of Example 3 was not measured, it is thought that the value of the peak intensity ratio is at least higher than that of the BEA type zeolite of Comparative Example 1. This is because when comparing Example 3 and Comparative Example 1, although the metal content is the same, the skeleton density is high.

Example 5
1 g of the obtained MSE type zeolite was immersed in 10 g of 1 mol/L ammonium chloride aqueous solution at 80°C, solid-liquid separation was performed, and washed with deionized water to obtain an NH ₄ type MSE type zeolite. 1 g of the obtained _NH4 type MSE type zeolite was immersed in 9.5 g of 0.05 mol/L copper (II) acetate aqueous solution at 60°C, separated into solid and liquid, washed with deionized water, and the wet powder was collected. did. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =20
Cu/Al=0.19

Example 6
An _NH4 type MSE type zeolite was obtained in the same manner as in Example 5. Cu ion exchange MSE type zeolite was prepared in the same manner as in Example 5, except that 1 g of the obtained _NH4 type MSE type zeolite was immersed in 6 g of 0.05 mol/L copper (II) acetate aqueous solution at 60°C. Obtained. The composition of the obtained Cu ion exchange MSE type was as follows. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =20
Cu/Al=0.15

Example 7
An _NH4 type MSE type zeolite was obtained in the same manner as in Example 5. 1 g of the obtained NH ₄ type MSE type zeolite was immersed in 5.3 g of a 0.05 mol/L cesium carbonate aqueous solution, solid-liquid separation was performed, and the wet powder was recovered by washing with deionized water. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cs ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The MSE type zeolite was ion-exchanged with Cs and H. The obtained MSE type zeolite containing Cs was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =20
Cs/Al=0.07

Example 8
An _NH4 type MSE type zeolite was obtained in the same manner as in Example 5. 1 g of the obtained NH ₄ type MSE type zeolite was immersed in 10 g of 0.1 mol/L sulfuric acid at 80°C, separated into solid and liquid, and washed with deionized water to obtain an H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was impregnated with 1 g of a 0.2 mol/L copper (II) acetate aqueous solution, and a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =22
Cu/Al=0.21

Example 9
An _NH4 type MSE type zeolite was obtained in the same manner as in Example 5. 1 g of the obtained NH ₄ type MSE type zeolite was immersed in 10 g of 1 mol/L sulfuric acid at 80°C, separated into solid and liquid, and washed with deionized water to obtain an H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was impregnated with 1 g of a 0.2 mol/L copper (II) acetate aqueous solution, and a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =58
Cu/Al=0.50

Example 10
An _NH4 type MSE type zeolite was obtained in the same manner as in Example 5. 1 g of the obtained _NH4 type MSE type zeolite was immersed in 10 g of 3 mol/L sulfuric acid at 80°C, solid-liquid separation was performed, and washed with deionized water to obtain an H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was impregnated with 1 g of a 0.2 mol/L copper (II) acetate aqueous solution, and a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
_SiO2 / _Al2O3 = ₇₆
Cu/Al=0.70

Example 11
An _NH4 type MSE type zeolite was obtained in the same manner as in Example 5. 1 g of the obtained NH ₄ type MSE type zeolite was immersed in 10 g of 5 mol/L sulfuric acid at 80°C, separated into solid and liquid, and washed with deionized water to obtain an H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was impregnated with 1 g of a 0.2 mol/L copper (II) acetate aqueous solution, and a wet powder was collected. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =181
Cu/Al=1.65

Example 12
1 g of the obtained MSE type zeolite was immersed in 6.7 g of 6 mol/L sulfuric acid at 100°C, separated into solid and liquid, and washed with deionized water to obtain H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was suspended in 5.8 g of a 0.05 mol/L copper (II) acetate aqueous solution, and a wet powder was recovered by evaporation to dryness. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu ion-exchanged MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Cu ion exchange MSE type zeolite was used as a hydrocarbon adsorbent.
_SiO2 / _Al2O3 = ₂₀₀
Cu/Al=2.09

Example 13
1 g of the obtained MSE type zeolite was immersed in 6.7 g of 6 mol/L sulfuric acid at 100°C, separated into solid and liquid, and washed with deionized water to obtain H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was suspended in a mixed aqueous solution of 0.03 mol/L gallium (III) nitrate and 0.015 mol/L platinum nitrate to a total of 5.2 g, and evaporated to dryness to form a wet powder. was recovered. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, an MSE type zeolite containing Ga and Pt having a composition with the following molar ratio was obtained. MSE type zeolite containing Ga and Pt was used as a hydrocarbon adsorbent.
_SiO2 / _Al2O3 = ₂₀₀
Ga/Al=1.74
Pt/Al=0.42

Example 14
1 g of the obtained MSE type zeolite was immersed in 6.7 g of 6 mol/L sulfuric acid at 100°C, separated into solid and liquid, and washed with deionized water to obtain H type MSE type zeolite. 1 g of the obtained H-type MSE type zeolite was suspended in 11 g of a 0.05 mol/L tin (II) acetate aqueous solution, and a wet powder was recovered by evaporation to dryness. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, an Sn-containing MSE type zeolite having a composition with the following molar ratio was obtained. The obtained Sn-containing MSE type zeolite was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =200
Sn/Al=0.93

Comparative example 5
1 g of commercially available H-type BEA-type zeolite (SiO ₂ /Al ₂ O ₃ molar ratio = 37) was suspended in 5 g of a 0.05 mol/L copper (II) acetate aqueous solution, and a wet powder was recovered by evaporation to dryness. The obtained wet powder was dried at 100° C. for 8 hours and heat treated at 550° C. for 3 hours in an air atmosphere. As a result, a Cu-containing BEA type zeolite having a composition with the following molar ratio was obtained. The obtained BEA type zeolite containing Cu was used as a hydrocarbon adsorbent.
SiO ₂ /Al ₂ O ₃ =37
Cu/Al=0.37

Regarding each hydrocarbon adsorbent of Examples 5 to 14 and Comparative Example 5, measurement samples, measurement of SiO ₂ /Al ₂ O ₃ molar ratio, and measurement of Cu/Al ratio were carried out in the same manner as in Examples 1 to 4 and Comparative Example. and the Cs/Al ratio.

Ga/Al ratio and Pt/Al ratio Measure the amount of Ga, Pt, and Al in the measurement sample by elemental analysis using the above-mentioned scanning fluorescent X-ray analyzer, and calculate Ga/Al and Pt/Al. did. In Example 13, the Ga amount was 1.9% by mass, the Pt amount was 1.3% by mass, Ga/Al was 1.74, and Pt/Al was 0.42. In Table 2, the sum of the amount of Ga and the amount of Pt is shown as the metal content ratio, and the sum of Ga/Al and Pt/Al is shown as the metal/Al ratio.

Sn/Al Ratio Using the above-mentioned scanning type fluorescent X-ray analyzer, the amount of Sn and the amount of Al in the measurement sample were measured by elemental analysis, and Sn/Al was calculated. In Table 2, the amount of Sn is described as the metal content ratio, and the Sn/Al is described as the metal/Al ratio.

Desorption amount/adsorption amount of toluene Each of the hydrocarbon adsorbents of Examples 5 to 14 and Comparative Example 5 was heated from 50°C to 500°C by a temperature raising reaction method while flowing toluene and water, and the adsorption temperature of toluene was determined. , desorption temperature, adsorption amount, and desorption amount were measured.
Specifically, 0.1 g of a measurement sample of each hydrocarbon adsorbent was filled into a quartz reaction tube of a flow reactor, and using a fixed bed flow reactor (fixed bed flow reactor) as a flow reactor, a sample containing 71 ppm of toluene and 10 While flowing an evaluation gas in an atmospheric atmosphere containing vol.% of water vapor at a rate of 1 L/min, the temperature was raised from 50°C to 500°C at a rate of 20°C/min using a heating reaction method to adsorb and adsorb toluene. Detached. To measure the adsorption and desorption of toluene on zeolite, the decrease in the amount detected by a downstream detector (VMS-1000F, manufactured by Shimadzu Corporation) with respect to the flow rate of toluene was used as the adsorption amount and purification amount. In areas where a value greater than the flow rate to the hydrocarbon adsorbent is detected, adsorbed hydrocarbons have been desorbed. The ratio of the total molar amount ZD ₂ desorbed from the hydrocarbon adsorbent at 170° C. or lower to the total molar amount ZD ₁ of toluene adsorbed at 50° C. or higher and lower than 170° C. (ZD ₂ /ZD ₁ × 100) is calculated as the ratio of toluene desorption. It was defined as the amount of separation/amount of adsorption. The results are shown in Table 2.
The adsorption/desorption behavior of toluene in the presence of water is complicated by the occurrence of adsorption, desorption, and re-adsorption, and the adsorption, desorption, and re-adsorption behavior depends on the SiO ₂ /Al ₂ O ₃ ratio, metal content, and metal species. Since the results are different, the evaluation was performed based on a temperature of 170° C., which is a temperature that can be compared only by adsorption and desorption.
Gas for evaluation of measurement conditions: 71 ppm of toluene, the balance being nitrogen (N ₂ ).
Atmosphere: An atmosphere containing 10% by volume of water vapor (H ₂ O). Steam is vaporized from a water tank, and the saturated water vapor pressure is adjusted depending on the temperature to create an atmospheric atmosphere containing 10% by volume of water vapor.

BET specific surface area For each hydrocarbon adsorbent of Examples 5, 11, 13, 14 and Comparative Example 5, the BET specific surface area was determined by the BET method from the nitrogen adsorption isotherm measured in accordance with ISO 9277 (JIS Z8330:2013). Calculated.

Heat treatment, toluene desorption amount/adsorption amount, peak intensity ratio, BET specific surface area Each of the hydrocarbon adsorbents of Examples 12 to 14 and Comparative Example 5 was heat treated under the above conditions, and then subjected to the above conditions. In the same manner as for each hydrocarbon adsorbent such as in Example 1 described above, the amount of desorption/adsorption of toluene was measured, the peak intensity ratio of the X-ray diffraction spectrum was measured, and the BET specific surface area was measured. Ta.
In addition, in Comparative Example 5, when confirmed by powder X-ray diffraction after heat treatment, it was confirmed that the skeleton structure of BEA type zeolite was not maintained, so adsorption measurement was not performed.

As shown in Table 2, the hydrocarbon adsorbents of Examples 5 to 12 (multipore zeolites containing specific metals) have a lower amount of toluene desorption/adsorption than the zeolite of Comparative Example 5. In other words, the amount of desorption is small compared to the amount of adsorption, and toluene can be stored up to a temperature of about 170°C, which makes it easy to evaluate the adsorption and desorption behavior of toluene on hydrocarbon adsorbents. It was confirmed that toluene could be desorbed from the hydrocarbon adsorbent at a relatively high temperature of 170° C. or higher. In addition, it was confirmed that the hydrocarbon adsorbents of Examples 12 to 14 had heat resistance, with the amount of toluene desorbed and adsorbed even after heat treatment. The zeolite of Comparative Example 5 did not adsorb toluene after the heat treatment.

As shown in Table 2, the hydrocarbon adsorbents of Examples 12 to 14 have higher peak intensity ratios in their X-ray diffraction spectra than the zeolite of Comparative Example 5, and their crystals are maintained even after heat treatment, resulting in improved heat resistance. It was confirmed that it is excellent.

As shown in Table 2, the hydrocarbon adsorbents of Examples 13 and 14 had a BET specific surface area ratio B/A of 0.5 or more and 0.9 or less before and after heat treatment. The structure of the multipore zeolite used as a hydrocarbon adsorbent showed little change, maintained its structure, and had heat resistance.

The hydrocarbon adsorbent according to the present disclosure is capable of adsorbing hydrocarbons and storing the adsorbed hydrocarbons up to a relatively high temperature, and desorbs the adsorbed and stored hydrocarbons at a relatively high temperature at which the catalyst can be activated. Since it can be separated, when used as a hydrocarbon adsorption part of an exhaust gas purification catalyst, the exhaust gas purification performance can be improved. Further, an exhaust gas purification catalyst using a hydrocarbon adsorbent can be suitably used to purify exhaust gas discharged from an internal combustion engine such as a four-wheeled motor vehicle or a two-wheeled motor vehicle.

1: Base material, 1a: Cell, 1b: Partition wall, 2: Hydrocarbon adsorption section, 3: Purification catalyst section, 3a: First purification catalyst section, 3b: Second purification catalyst section, 10: Exhaust gas purification catalyst (first (exhaust gas purification catalyst or second exhaust gas purification catalyst), 20: internal combustion engine, 30: exhaust gas flow path, 40, 50: exhaust gas purification catalyst, 100, 200, 300: exhaust gas purification system.

Claims (22)

At least one metal selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, Ba, Mn, Ni, Cu, Zn, Ga, Rh, Pd, Ag, Sn, Sc and Pt. Contains multi-pore zeolite outside the zeolite skeleton,
The content ratio of the metal is 9% by mass or less with respect to the multipore zeolite containing the metal,
The multipore zeolite is an MSE type zeolite or an EON type zeolite, in which the SiO ₂ /Al ₂ O ₃ molar ratio of the multipore zeolite is 20 or more and 600 or less,
In the multipore zeolite, at least a portion of the metal is present in small pore cages;
A hydrocarbon adsorbent having a metal/Al ratio, which is a molar ratio of the metal and Al contained in the multi-pore zeolite, within a range of 0.05 or more and 2.5 or less . The hydrocarbon adsorbent according to claim 1, wherein the multipore zeolite has a SiO ₂ /Al ₂ O ₃ molar ratio of 58 or more and 400 or less. The hydrocarbon according to claim 1, wherein the metal is at least one selected from the group consisting of Cs, Mn, Ni , Cu, Zn, Ga, Rh, Pd, Ag, Sn, Sc, and Pt. adsorbent. The hydrocarbon adsorption according to any one of claims 1 to 3, wherein the metal/Al ratio, which is the molar ratio of the metal and Al contained in the multipore zeolite, is within the range of 0.07 or more and 2.16 or less. Material. The hydrocarbon adsorption according to any one of claims 1 to 4, wherein the multipore zeolite includes large tunnel-shaped pores and small pore cages whose largest ring is 8-membered or less. Material. The hydrocarbon adsorbent according to any one of claims 1 to 5, wherein the multipore zeolite contains phosphorus. The hydrocarbon adsorbent according to claim 6, wherein the P/Al molar ratio in the phosphorus-containing multipore zeolite is 0.4 or more and 1.1 or less. The hydrocarbon adsorbent according to any one of claims 1 to 7, wherein the multipore zeolite has a BET specific surface area A of 400 m ² /g or more and 1000 m ² /g or less. The specific surface area ratio B/A of the BET specific surface area A of the multi-pore zeolite before heat treatment and the BET specific surface area B of the multi-pore zeolite after heat treatment that satisfies the following heat treatment conditions (1) to (5) is 0. The hydrocarbon adsorbent according to claim 8, which is within the range of 35 or more and 1 or less.
Heat treatment conditions (1) Temperature: 850℃
(2) Time: 25 hours (3) Atmosphere: Atmosphere containing 10 volume % water vapor (H ₂ O), vaporize water vapor from a water tank, adjust the saturated water vapor pressure depending on the temperature, and create 10 volume % water vapor. The atmosphere shall be one containing:
(4) Model gas distribution mode: In the ignition, combustion and charging (FC) mode, the following model gas (5) is alternately distributed at 3 L/min for 80 seconds and Air at 3 L/min for 20 seconds.
(5) Model gas: The total of C ₃ H ₆ , O ₂ and N ₂ is 3 L/min, C ₃ H ₆ is 70 mL/min, O ₂ is 70 mL/min, and the balance is N ₂ . The MSE type zeolite has a peak intensity at a diffraction angle (2θ) representing the (420) plane of the X-ray diffraction spectrum of 21.7° ± 1.0°, and the Peak intensity ratio D/C of the peak intensity C of the (420) plane of the MSE type zeolite and the peak intensity D of the (420) plane of the MSE type zeolite after heat treatment that satisfies the following heat treatment conditions (1) to (5). The hydrocarbon adsorbent according to any one of claims 1 to 9 , wherein is within the range of 0.3 or more and 1.5 or less.
(1) Temperature: 850℃
(2) Time: 25 hours (3) Atmosphere: Atmosphere containing 10 volume % water vapor (H ₂ O), vaporize water vapor from a water tank, adjust the saturated water vapor pressure depending on the temperature, and create 10 volume % water vapor. The atmosphere shall be one containing:
(4) Model gas distribution mode: In the ignition, combustion and charging (FC) mode, the following model gas (5) is alternately distributed at 3 L/min for 80 seconds and Air at 3 L/min for 20 seconds.
(5) Model gas: The total of C ₃ H ₆ , O ₂ and N ₂ is 3 L/min, C ₃ H ₆ is 70 mL/min, O ₂ is 70 mL/min, and the balance is N ₂ . A base material, a hydrocarbon adsorption section containing the hydrocarbon adsorption material according to any one of claims 1 to 10 on the base material, and a purification catalyst section on the hydrocarbon adsorption section. Also, exhaust gas purification catalyst. The purification catalyst section includes a first purification catalyst section containing at least one of Rh and Pt, and a second purification catalyst section containing at least one of Pd and Pt; The exhaust gas purification catalyst according to claim 11 , further comprising a second purification catalyst section disposed on the side of the hydrocarbon adsorption section and on the first purification catalyst section. 13. The first purification catalyst section includes a cerium oxide-zirconium oxide composite oxide (CeO ₂ -ZrO ₂ ) having a CeO ₂ content of 15% by mass or more and 30% by mass or less. exhaust gas purification catalyst. a base material, a hydrocarbon adsorption section containing the hydrocarbon adsorption material according to any one of claims 1 to 10 on the base material, and Rh, and Pd on the hydrocarbon adsorption section. An exhaust gas purification catalyst equipped with a purification catalyst section. internal combustion engine;
a first exhaust gas purification catalyst provided on the upstream side in the exhaust gas flow path connected to the internal combustion engine;
An exhaust gas purification system comprising: a second exhaust gas purification catalyst provided in the exhaust gas flow path downstream of the first exhaust gas purification catalyst in the exhaust gas flow direction;
The second exhaust gas purification catalyst is the exhaust gas purification catalyst according to any one of claims 11 to 14 ,
An exhaust gas purification system, wherein the content ratio of platinum group metal in the second exhaust gas purification catalyst is 0.1 g/L or more and 3.0 g/L or less based on the volume of the second exhaust gas purification catalyst. internal combustion engine;
An exhaust gas purification system comprising a single exhaust gas purification catalyst in an exhaust gas flow path connected to the internal combustion engine,
An exhaust gas purification system, wherein the exhaust gas purification catalyst is the exhaust gas purification catalyst according to any one of claims 11 to 14 . internal combustion engine;
An exhaust gas purification system comprising a plurality of exhaust gas purification catalysts provided in an exhaust gas flow path connected to the internal combustion engine,
An exhaust gas purification system, wherein the first exhaust gas purification catalyst disposed most upstream in the exhaust gas flow direction among the plurality of exhaust gas purification catalysts is the exhaust gas purification catalyst according to any one of claims 11 to 14 . . Combustion exhaust gas containing hydrocarbons is brought into contact with the exhaust gas purification catalyst according to any one of claims 11 to 14 , and after the hydrocarbons are adsorbed on the exhaust gas purification catalyst, A method for treating exhaust gas comprising desorbing hydrocarbons from the exhaust gas purification catalyst at a temperature. preparing a raw material mixture containing a silica source, an aluminum source, an alkali metal source, an organic structure directing agent, and water;
The raw material mixture is heated and crystallized to form SiO ₂ /Al ₂ O ₃ Obtaining a multipore zeolite that is an MSE type zeolite or an EON type zeolite with a molar ratio of 20 to 600;
At least one metal selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, Ba, Mn, Ni, Cu, Zn, Ga, Rh, Pd, Ag, Sn, Sc and Pt. introducing into the small pore cage of the multi-pore zeolite,
The content ratio of the metal is 9% by mass or less with respect to the multipore zeolite containing the metal,
A method for producing a hydrocarbon adsorbent comprising a multi-pore zeolite, wherein the metal/Al ratio, which is the molar ratio of the metal to Al contained in the multi-pore zeolite, is in the range of 0.05 or more and 2.5 or less. The method for producing a hydrocarbon adsorbent according to claim 19, comprising the step of bringing the multi-pore zeolite into contact with a phosphorus-containing compound or a sulfur-containing compound to make the multi-pore zeolite contain phosphorus or sulfur. Measuring the BET specific surface area A of the multi-pore zeolite, and measuring the BET specific surface area B of the multi-pore zeolite after heat treatment that satisfies the following heat treatment conditions (1) to (5),
The BET specific surface area A of the multipore zeolite before heat treatment is within the range of 400 m ² /g or more and 1000 m ² /g or less,
19 or 19 above, wherein the specific surface area ratio B/A of the BET specific surface area A of the multi-pore zeolite before heat treatment and the BET specific surface area B of the multi-pore zeolite after heat treatment is within the range of 0.35 or more and 1 or less; 21. The method for producing a hydrocarbon adsorbent according to 20 .
Heat treatment conditions
(1) Temperature: 850℃
(2) Time: 25 hours
(3) Atmosphere: An atmosphere containing 10% by volume of water vapor (H ₂ O). Steam is vaporized from a water tank, and the saturated water vapor pressure is adjusted depending on the temperature to create an atmospheric atmosphere containing 10% by volume of water vapor.
(4) Model gas distribution mode: In the ignition, combustion and charging (FC) mode, the following model gas (5) is alternately distributed at 3 L/min for 80 seconds and Air at 3 L/min for 20 seconds.
(5) Model gas: The total of C ₃ H ₆ , O ₂ and N ₂ is 3 L/min, C ₃ H ₆ is 70 mL/min, O ₂ is 70 mL/min, and the balance is N 2 _. The MSE type zeolite has a peak intensity at a diffraction angle (2θ) position of 21.7° ± 1.0°, where the diffraction angle (2θ) representing the (420) plane of the X-ray diffraction spectrum is
Measuring the peak intensity C of the (420) plane of the X-ray diffraction spectrum of the MSE type zeolite, and measuring the peak intensity C of the (420) plane of the MSE type zeolite after heat treatment that satisfies the following heat treatment conditions (1) to (5). comprising measuring the peak intensity D;
The carbonization according to 19 or 20 above, wherein the peak intensity ratio D/C of the peak intensity D of the MSE type zeolite after heat treatment to the peak intensity C of the MSE type zeolite is within the range of 0.3 or more and 1.5 or less. Method for manufacturing hydrogen adsorbent.
Heat treatment conditions
(1) Temperature: 850℃
(2) Time: 25 hours
(3) Atmosphere: 10% by volume of water vapor (H ₂ In the atmosphere containing O), water vapor is vaporized from a water tank, and the saturated water vapor pressure is adjusted depending on the temperature to create an atmospheric atmosphere containing 10% by volume of water vapor.
(4) Model gas distribution mode: In the ignition, combustion and charging (FC) mode, the following model gas (5) is alternately distributed at 3 L/min for 80 seconds and Air at 3 L/min for 20 seconds.
(5) Model gas: C ₃ H ₆ , O ₂ and N ₂ The total of C is 3L/min, and C ₃ H ₆ is 70mL/min, O ₂ is 70 mL/min, the remainder is N ₂ It is.